Analysis of Heavy Metal Loading Optimization Through Criticality Calculation on RDE

The RDE (Indonesian Experimental Power Reactor) designed to produce 10 MW thermal with cylindrical core. The HGTR (High Temperature Gas-cooled Reactor) reactor technology with passive inherent safety is adopted. This RDE reactor core is designed to produce high temperature output range about 700°C, making it particularly suitable for cogeneration purposes such as electricity, desalination water production and industrial high temperature heat application. The improvement of performance and neutronic safety design parameter which strongly affects to the neutron moderation ratio such as the HM (Heavy Metal) loading optimization is important to ensure that. Therefore HM loading through the criticality calculation of the RDE reactor core using VSOP'94 code and MCNP6 coupled with ENDF/BII library is performed. Calculations using VSOP'94 code utilize DATA-2, ZUT-DGL, BIRGIT and VSOP-CITATION modules, whereas the calculations with MCNP6 start from the TRISO kernel modeling, fuel pebble and 3-D full core modeling. The optimization of HM loading calculation on core criticality is done through simulating of the heavy metal loading (HM) variation level from 1-15 gHM/pebble using several enrichment of 235U from 8%, 10%, 12% 14% and 17% using VSOP'94 and MCNP6 code through RDE core criticality with good results. The smallest difference of effective multiplication factor on RDE core criticality (below 1%) between two calculations with VSOP'94 and MCNP6 occurs at the HM loading level of 5 gHM/pebble at all 235U enrichment levels. At 17% enrichment, a similar trends to other enrichment, gives the maximum core criticality on HM loading of 8 gHM/pebble with effective multiplication factor of 1.17860 and 1.22458, respectively for VSOP'94 and MCNP6 with a difference of -3.75476%. As for HM loading 5 gHM/pebble calculations using VSOP'94 and MCNP6 each gives effective multiplication factor value of 1.16096 and 1.16666, respectively, with a difference of about -0.48857%.